Carbon Tetraoxide: Theoretically Predicted and Experimentally Detected

Abstract

The current interest in CO n (n > 2) oxides reflects the growing recognition of their role in different research areas. First, CO n species are key intermediates in the reactions of atomic and molecular oxygen with the lower oxides of carbon, hydrocarbons, and other organic molecules.[1] Furthermore, CO n oxides and their ions are relevant to the chemistry of the terrestrial [2] and planetary [3] atmospheres. More importantly, members of the CO n family are potential high-energy density materials (HEDM), the next generation of environmentally benign propellants and explosives.[4] CO 4 is of special interest, since ab initio MP2, QCISD and MP2/6-31G* calculations [5][6][7] have identified a CO 4 D 2d 1 A 1 singlet as a metastable species that releases from 80 to 93 kcal mol À1 upon dissociation into CO 2 (X 1 AE + ) and O 2 (a 1 D). Another isomer of C 2v symmetry has been identified on the potential energy surface (PES) of the lowest 1 A 1 singlet state, and two local C 2v minima have been located on the low-lying, excited triplet PES. [7] In summary, the available theoretical results identify two singlets of D 2d and C 2v symmetry as the lowest energy CO 4

The Oxygen-Rich Carboxide Series: COn (n = 3, 4, 5, 6, 7, or 8)

“…[26][27][28][29] Cacace and co-workers recently reported the experimental detection of this CO 4 molecule. 30 They surmised, based upon their own and previous theoretical studies, that the lower-energy isomer, Figure 1b, would proceed to dissociation without a barrier, and that the D 2d structure, Figure 1c, would thus be the one observed. This work shows that this is a truly metastable molecule and is attractive for further research.…”

Bicyclic CN2O2 as a high-energy density material: promising or not?

“…[2][3][4][5][6] What makes a molecular HEDM? Carbon (C), nitrogen (N) and oxygen (O) are very important elements both on Earth and in space.…”

“…Thus, study of such HEDMs has never ceased, though the number of successful examples grows slowly because of the synthetic difficulties. [2][3][4][5][6] What makes a molecular HEDM? First, the most feasible pathway of the molecule should release a large amount of energy upon unimolecular decomposition to CO, N 2 or CO 2 .…”

Monocyclic and bicyclic CO4: how stable are they?

“…Besides CO and CO 2 that have a well-known direct bearing on human life, the high-order carboxides CO n (n > 2) have been receiving growing attention in the last decades. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] They can be produced in the reactions of oxygen (atomic or molecular) with the lower oxides of carbon, hydrocarbons, and other organic molecules. 26 CO n and their ions are also relevant to the chemistry of the terrestrial 27 and planetary 28 atmospheres.…”

“…Cacace and coworkers reported the rst detection of neutral CO 4 and, based on their own and previous computational studies, assigned it the bicyclic 1 2 structure with a lifetime exceeding 1 ms in the isolated gas state. 15 Later in 2007, Jamieson et al reported on the detection of the monocyclic isomer 1 1 via low temperature infrared spectroscopy of CO 2 ice. 19 CO 4 has also been the subject of other computational 14,17,23,24 and experimental 24 studies.…”